1. Field of the Invention
My invention relates to methods, apparatus and materials for increasing the percentage of mammalian offspring of either sex, and more particularly to immunological methods of increasing the percentage of mammalian offspring of either sex, apparatus for carrying out such immunological methods, and seminal fluid materials obtained by using such methods, containing either male-determining spermatazoa or female-determining spermatazoa in substantial perponderance as compared with naturally occurring, unmodified semen.
2. Description of the Prior Art
Mechanical methods increasing the percentage of mammalian offspring of either sex by providing seminal fluids containing a surplus of either male-determining spermatazoa of female-determining spermatazoa with the aid of the difference in density between male-determining spermatazoa and female-determining spermatazoa are taught in the prior art, e.g., in abandoned United States Patent application Ser. No. 443,473, in United States Patent application Ser. No. 814,906, and in a paper by E. Schilling, "Separation of Bull Sperm by Sedimentation and Centrifugation and the Sex of the Born Cows," Zeitschrift fur Saugertierkunde, Volume 31, No. 4, pages 314-323 (1966). Such methods are known, however, to be characterized by reduced sperm survivability, and by reduced viability of the surviving sperm.
The speculation that immunological means can be used to increase the percentage of mammalian offspring of either sex is discussed in a paper entitled "Sex Ratio in Progeny of Mice Inseminated With Sperm Treated With H-Y Antiserum" by Bennett and Boyse, Nature, Volume 246, Nov. 30, 1973, pages 308 and 309.
An immunological method of increasing the percentage of mammalian offspring of either sex is disclosed in United States Pat. No. 3,687,806, issued to Gustaaf J. van den Boevenkamp on Aug. 29, 1972. The method of this patent required as a starting material a sperm fraction containing a surplus of either male-determining spermatazoa or female-determining spermatozoa isolated in accordance with the aforementioned abandoned application Ser. No. 443,473, the other above-mentioned application Ser. No. 814,906, or the aforementioned Schilling article, or closely related mechanical methods. Thus, the method of the aforementioned U.S. Pat. No. 3,687,806 necessarily suffers to a greater or lesser degree from the disadvantages of said mechanical methods, i.e., reduced sperm survival and reduced viability of the surviving sperm.